The present invention relates to a magnetic process for determining a trajectory for finding or reaching a moving or fixed magnetic object. This process can consist of guiding a moving vehicle or contrivance to a magnetic object. The invention also relates to an apparatus for performing the process.
The problem of guiding a moving vehicle in space occurs frequently in the most varied fields, particularly in robotics or for seeking objects or persons (e.g., skiers lost in an avalanche).
The known processes for guiding a moving vehicle to a fixed or moving object usually use wave techniques of the radar or infrared type. All these processes are based on the location of the object in a moving reference frame linked with the vehicle.
The invention applies to the guidance of a moving vehicle to a magnetic object. The magnetic object can be naturally magnetic, e.g. if it has ferromagnetic materials. It can also be made magnetic by adding ferromagnetic elements to it, or by giving it a magnetic field source, e.g. with the aid of a coil through which passes a direct or alternating current. In the later case, the object to which it is wished to guide the moving vehicle or contrivance is then equivalent to a magnetic multipole. A known magnetic guidance process based on the location of an object in a moving reference frame linked with the vehicle, like the known wave processes referred to hereinbefore, suffers from disadvantages.
That is, the process requires the modelling of the magnetic field and the solution of the reverse problem caused by location on the basis of the measurements performed. However, this modelling presents difficulties, because the analytical model defining the magnetic field produced by the object evolves in time as the vehicle moves towards the object. In particular, certain multipolar terms in the expression of the magnetic field produced by the magnetic multipole (i.e. the object) are negligible with respect to the accuracy of the measurements performed by the vehicle when the latter is at a great distance from the object, whereas this no longer applies when the vehicle approaches the object.
Furthermore, a magnetic process based on the location of the object is also made difficult because it has to take account of the earth's magnetic field or the geomagnetic field.